1. Field of the Invention
This invention relates generally to training apparatus, and more particularly, but not by way of limitation, to a rod wrenching table for use in training persons to assemble sucker rods connected to a pump to be lowered into an oil well.
2. Description of the Prior Art
After an oil well has been completed, a downhole pump is often installed in the well. This downhole pump is a reciprocating plunger pump which is actuated by a string of sucker rods connected between the pump and a reciprocating horse's head located on the ground surface. The sucker rods are solid steel rods having threaded pin connections at both ends, with a square wrenching shoulder adjacent the pin connection. Adjacent sucker rods are connected by means of a threaded female coupling which is often referred to as a rod box.
The installation of a downhole pump of this type in an oil well is normally carried out as follows. Initially the pump and the sucker rods are all located on the ground surface before they are inserted into the oil well. The lower end of a first sucker rod is connected to a coupling attached to the pump. The upper end of the first sucker rod is then engaged with an elevator. An elevator is a device which engages a flared shoulder below the square wrenching shoulder so as to support the sucker rod. The elevator is connected to a block and tackle assembly located on the rigging above the well so that the elevator and sucker rods may be lowered and raised by the block and tackle assembly.
The pump and the first sucker rod are then lowered into the oil well until the first elevator engages the upper end of the well casing. At this point it is necessay to attach a second sucker rod to the first sucker rod.
The two sucker rods are connected by means of a coupling or rod box as previously mentioned. Typically, the coupling or rod box will already be made up upon one or the other of the first and second sucker rods.
A second elevator is engaged with the upper end of the second sucker rod and the second sucker rod is lifted to a position slightly spaced above the upper end of the first sucker rod.
Then first and second hammer rod wrenches, as are familiar to those skilled in this art, are engaged with the square hammering shoulders of the upper end of the first rod and the lower end of the second sucker rod. The second sucker rod is resiliently suspended from the rigging so that a downward force may be exerted upon the second sucker rod thereby pulling it into engagement with the first sucker rod. It will be understood that this engagement is through the means of the rod box. The second sucker rod is then threadedly connected to the first sucker rod by means of the interconnecting rod box.
The most difficult part of assembling these sucker rods is to learn to assemble them very quickly. This is important because a great number of rods are required to be assembled when intalling a pump, and downtime on the oil well is very costly. After the threaded engagement between the first and second sucker rods is initiated, the second sucker rod is spun by means of the second hammer rod wrench. This spinning is continued until the shoulders of the pin and box connections are mated. Then, it is necessary to hammer the two sucker rods together to ensure that the threaded joint is made up tightly. This hammering is accomplished by means of the hammer rod wrenches.
The hammer rod wrenches include a spring loaded swivel head which allows the worker using the wrenches to back off approximately 30.degree. on the wrenches without actually turning the rod, then to slam the wrenches back together so that the wrench builds up a substantial momentum before force is actually transferred to the sucker rod, thereby providing a hammering effect which tightly wrenches the pin and box connections together.
Similarly, this hammer effect is used to break the threaded connections when the rods are being disassembled as the pump is being retrieved from the well. Once the threaded connection is broken, then the second hammer rod wrench is used to spin the uppermost rod at the connection so as to rapidly unscrew the pin and box connections.
The apparatus located at the oil well site, and the methods just described, are old in the art, and the apparatus and tools mentioned are well known to those skilled in the art.
A problem encountered in the assembly and disassembly of sucker rods is that a considerable degree of skill is required in order to be able to properly and rapidly assemble and disassemble the sucker rods. This is a skill which can only be obtained by practice and experience. The problem is that customers of service companies who install these pumps are reluctant to let untrained personnel work on their equipment, and at the very least are dissatisfied when delays are caused because of novice personnel who are not able to rapidly conduct the assembly or disassembly job.
Prior to the present invention, there has been no satisfactory manner of training personnel to accomplish this task other than by on the job training with the accompanying difficulties mentioned.
The present invention provides a training apparatus which very closely simulates the conditions present in the field when assembling and disassembling sucker rods. By means of this training apparatus, personnel may be trained before they ever go into the field, so that they will be relatively skilled in this task the first time they actually go into the field to do a job for a customer.